Saturday, June 24, 2006

I haven't blogged about sound on the battlefield yet, so this new StrategyPage article is as good a one to start with as I could hope for.

This produces another unique battlefield sound portrait. You know American troops are at work when one shell goes off, followed by a few shots. No shouting, American troops use individual radios, hand signals and night vision equipment. They move fast, using minimal firepower. Less risk of friendly fire, or collateral damage (civilian casualties or property damage.) Battlefields have never sounded like this.

Thursday, June 22, 2006

Unless you either browse US patents or write US patent applications, this probably is not of interest to you and I apologize for this off-topic posting.

The reason I am posting it is that for those of us who do use the USPTO (US Patent and Trademark Office) website, one of the big frustrations most everyone has is the inability to view the patent images. For technical reasons, Apple Quicktime tries to load the TIFF images of the patents and drawings, but cannot do it correctly (so you get none or only part of the image). Like most people who have not discovered "the secret" (after having similarly failed with all the other advertised plug-ins and such), I adopted a work-around using a free patent server, but this was awkward.

Anyway, to make a long story shorter, I have found an image viewer that works in Firefox and IE - Alternatiff. Here is the link. I hope it saves you the frustration I've experienced over the last several years.

Monday, June 19, 2006

There have been been devices on the market that detect lenses for some time , but a system was recently prototyped that is, to my knowledge, the first that goes beyond simple detection and actively counters the operation of at least some digital camera systems.

(Disclosure: my company markets a Russian-manufactured device that detects optics.)

Engineers at the Georgia Institute of Technology have prototyped a system to automatically detect and temporarily blind the image sensors used in digital cameras. Detection is accomplished by exploiting a characteristic of digital image sensors - by their nature, they reflect light back to the source (i.e. retroreflection).

Automatically finding reflections isn't all that difficult, but then you have to filter out the false positives (reflections which aren't really from camera sensors) and guide beams of light at the remaining reflectors. This article describes some general details of the method.

Proposed uses include thwarting people making pirated videos in cinemas, paedophiles making videos of children visiting shopping mall Santas, espionage in government buildings, and so on. The technique will not work against still image cameras that use a shutter to shield the sensor until a picture is taken, which includes some digital cameras and all film cameras.

Friday, June 16, 2006

Photonics.com has an article on two patent applications related to a technique to identify which digital camera took a particular photograph. The inventors are researchers at State University of New York at Binghamton (NY, USA). The lead researcher is Jessica Fridrich.

The general idea of identifying digital cameras by their 'dead' (i.e. non-functioning) pixels or other characteristics of their image sensor has been discussed over the past few years and some techniques have emerged to identify brands of cameras (due to their manufacturers' standard implementation of internal image processing and such) and even individual cameras.

The new technique described in the article is based on extracting a very weak noise pattern that is present in all digital photographic images due to inhomogeneities in solid-state sensors used. The inventors claim that their technique can extract this pattern from a single image. Since it is based on a pattern derived from the several million pixels present in most current digital cameras, they intuit that it may indeed be unique. This is a claim that has to be made very, very carefully. With scientific (in this case, forensic) analysis that may be used in court, it is especially important to not claim that a signature is "unique" until it can be proven to an accepted legal standard, such as Daubert in the USA.

LiveSience reports on work presented at the spring meeting of the Acoustical Society of America that compares the hearing of a broad cross-section of Americans over time. What was surprising is that despite technical and economic factors during the last 35 years (think boom boxes, growth in construction and its associated noise, explosion in jet travel, etc.), the hearing of the average American is about the same instead of significantly worse. For completeness, I should also note that women's hearing was better than men's, but that shouldn't be surprising (shooting ranges, motorbikes, and movies with lots of explosions immediately come to mind as possible explanations for that!).

Functional magnetic resonance imaging ( fMRI) has reportedly yielded another insight into how the human brain functions. fMRI is a non-invasive imaging technique that exploits a particular modern instrument's ability to sense the magnetic properties of water in order to detect changes in the rate that tissue is using oxygen. How rapidly a tissue uses oxygen is a good indicator of how much work it is doing. So, when using fMRI to study a human doing mental tasks, a scientist can tell which areas of the brain are active (functioning).

Using the fMRI technique in a controlled study, French researchers at Université Pierre et Marie Curie and Ecole Normale Supérieure have reportedly discovered that Broca's area (located near the left temple), along with its companion area on the right side, is involved in more than just organizing speech - it also organizes (plans) many other things. This planning ability is one of the major things that distinguishes human intelligence from that of other species.

Saturday, June 10, 2006

A poet at MIT (Massachusetts Institute of Technology, USA) has developed a machine that allows legally blind people who have at least some healthy retina left to see images that the machine projects and focuses in their eyes. It has been tested on at least 10 legally blind people with good results.

An analogy would be a hearing aid for (partially) deaf people. A partially deaf person's hearing does respond to sound but in many cases it requires significant amplification first, which is what the hearing aid does. In this visual system, the machine provides amplification and focusing of light instead. Pretty neat! Maybe this has been done before since it seems to be a pretty obvious solution to the problem, but if it hasn't, then the lead designer (Elizabeth Goldring, a senior fellow at MIT's Center for Advanced Visual Studies) deserves even more credit.

This week's Physics News update email brought to my attention some acoustics research presented at the yearly conference of one of my professional societies, the Acoustical Society of America. The work was performed by researchers from Penn State University (USA) and is about simulating how sound travels on the planet Mars. Here is an excerpt:

... detailed computer calculations that simulate how sound travels through the Martian atmosphere, which is much thinner than Earth's (exerting only 0.7% of the pressure of our atmosphere on the surface) and has a very different composition (containing 95.3% carbon dioxide, compared to about 0.33% on our planet). The loss of 1999's Mars Polar Lander, which was to record sounds directly on the planet, has compelled researchers to find other means to study how sound travels there.

This is a technical piece of work, but if you have a science background of any type it should be clearly understandable. For those who are into this type of thing, the simulation algorithm used was Direct Simulation Monte-Carlo. An overview of the paper in layman's language is available at the Acoustical Society's website. It also includes a link to a video (which unfortunately I haven't been able to get to play yet due to some codec error) (UPDATE: they have fixed the problem)

Monday, June 05, 2006

A news report in The Examiner (Eastern Jackson County, Missouri, USA - registration may be required) brought to mind the differences in 'recovered' versus 'surveillance' evidence. In this specific case the authorities have arrested and arraigned a couple on charges related to three victims who were variously kidnapped, sexually molested, assaulted and murdered. Allegedly, two adult female victims were murdered and one female child victim was kidnapped and assaulted. According to the newspaper account, the forensic evidence includes:

... an address book that contained references to "choking," "chasing" and "sexual desires." Other evidence includes duct tape with hair; a video camera; and a videotape of Spicer being sexually assaulted and beaten.

Sanders said more than 20 videotapes and some audio tapes, including at least one 90-minute tape, were found in the truck Davis, 41, and Riley, 39, crashed in Barton County, near Lamar, Mo., last week. They were found by Barton County Sheriff's officers. Police also found videotapes where Davis worked. The tapes are similar to the one found at Davis' apartment and show Spicer and Ricci being abused.

I don't know anything more about this case than what I read in the article, but the point I want to make is a general one about the challenges of performing audio and video forensics on evidence that is recovered by a crime scene investigation.

When a technical surveillance unit (TSU) collects audio and/or video, by and large, the forensic examiner can reasonably expect that any media received for examination will have been recorded using standard equipment and procedures, as well as the fact that most, if not all, of it will be relevant.

Note: This does vary, of course, due to skills, training, equipment maintenance, equipment budgets, and operational constraints (e.g. time and opportunity). Just because it was recorded by a tech surveillance unit doesn't mean that it will be perfect; however, the odds that it will be useable are improved substantially.

Not so with recovered evidence - who knows when the last time the tapes in the answering machine found at the crime scene were changed? Probably not in the last two years, Murphy's Law says! Was an external or internal mic used on the video camcorder? Yeah, right. Was the lens clean on the camera? Was the right lens used for the lighting and distance involved? Was the audio and/or video over-compressed? Were the batteries freshly charged? Did he (i.e. the suspect) try to perserve the evidence or destroy it? Did the "black box" come through the crash unscathed? The list goes on and on...

The long and short of it is that recovered audio/video evidence is like a grab bag at a tourist trap - you never know what you are going to get, but you can pretty much expect that it won't thrill you. And in cases such as (videotaped) sexual assault and murder, it can be as, or even more, grim than what the classic 'wet' forensic disciplines deal with (e.g. blood, semen, autopsies). In the context of this post, recovered evidence is the most challenging type that an audio/video examiner can receive, by far.

Friday, June 02, 2006

What do you get when you cross acoustics and lasers? The answer is a SASER (Sound Amplification by Stimulated Emission of Radiation). This has been done before but there is a new implementation out. Work was by University of Nottingham in the UK and the Lashkarev Institute of Semiconductor Physics in the Ukraine and is in the 2 June 2006 edition of Physical Review Letter.

The University of Aston will shortly, (hopefully by mid-June), be inviting applications for a three year PhD scholarship in the areas of Forensic Linguistics and Language and the Law, in memory of Phill Newbury. The scholarship will be available from October 1st and will be worth a little over £15,000 a year. For a student resident in the European Union, this will be sufficient to pay the full university fees, plus a maintenance allowance of £12,000. Non-EU students are also welcome to apply, but sadly the maintenance allowance will be lower as the university fees, at some £8,750, are considerably higher.